Energy Efficient Air Compressor System

ABSTRACT

A system and method for compressing a quantity of air is proposed. The air compressor system and method comprises an air compressor for compressing a quantity of air, a supply air fan for supplying air to maintain a pressure set point at the inlet of the compressor, and a static pressure sensor configured to detect the static pressure of the inlet of the compressor. The embodiment also includes a variable frequency drive serving the supply air fan and operable to modulate the speed of the fan to maintain the static pressure at the inlet of the compressor at a set point. An air pressure regulator valve is provided in connection with and operable to regulate the air pressure of the quantity of air. An air pressure receiver stores air to minimize pressure fluctuations. A dryer and air filter are located upstream of said air compressor in embodiments to save energy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/824,067 filed on May 16, 2013.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

1. Technical Field

The disclosed embodiments generally relate to air compressor systems and, more particularly, to air compressors used in industrial manufacturing plants, instruments, and other applications.

2. Description of the Related Art

An air compressor system decreases the volume and increases the pressure of a quantity of air by mechanical means. Compressed air has a lot of potential energy because air expands rapidly upon the removal of external pressure. The force of compressed air can be used to power tools and devices that use air.

FIG. 1 is an illustration of the components of a conventional air compressor system in the prior art. Typical prior art air compressor system 100 is comprised of air filter 102, compressor 104, lubricant cooler 106, air separator 108, coalescing separator 110, after-cooler 112, moisture separator 114, dryer 116, air filter 118, air receiver 120, heater 122, and air pressure regulation valve 124. Air filter 102 is typically located at the entrance of prior art air compressor system 100. Compressor 104 is located downstream of air filter 102 and filters out particles in the air to protect compressor 104 from physical damage. Compressors use volumetric or centrifugal compression to increase the air pressure so that it reaches the required level. The compressor may be lubricant free or lubricant injected. In the figure, air separator 108 is located downstream of air compressor 104 and functions to separate the air and the lubricant. Notably, however, an air separator is not a necessary component in lubricant free compressors. Lubricant cooler 106 cools lubricants to a lower temperature range (typically in the range of between 30° C. to 50° C.) to ensure the safe and efficient operation of the compressor. If a lubricant injected compressor is used, coalescing separator 110 separates lubricant from the air to prevent the lubricant from being trapped in after-cooler 112 where the air temperature was lowered. Compressed air is cooled by after-cooler 112 to a lower temperature range (typically within the range of 30° C. to 50° C.) in order to minimize the capacity of the dryer and associated operating costs. After passing through the after-cooler, the air becomes saturated. Cooling is typically accomplished using air or water cooled heat exchangers. Moisture separator 114 removes condensed liquid from the air stream. Dryer 116 removes moisture in the system to satisfy the process moisture requirement. Particulate air filter 118 is generally installed downstream of dryer 116 to prevent adsorbed matter from entering the distribution system. Since air is often saturated after passing through air filter 118, any temperature drop along the pipe has the potential to cause condensation (and thus create issues during industry processes). Air receiver 120 stores enough air to minimize pressure fluctuations if the load changes, and heater 122 is equipped to heat the air and prevent condensation in the duct. Air pressure regulation valve 124 regulates the air pressure at a level required for the operation of the process equipment.

The previously described prior art compressor system and those like it have a variety of drawbacks. First, the compressor efficiency is low due to the relatively high temperature and presence of excessive moisture. This can cause up to 6% more compressor power energy consumption. Due to the high air temperature and the presence of excess moisture, the compressor has to be sized up to 10% higher in order to meet the required capacity in summer weather conditions. Pressure losses of up to 30% of the compressor head occurs through the filters, dryers, and separators. Up to 30% of the total compressor power is also consumed by the filters, dryers, and separators. The dryer and after-cooler also consume as much as 15% of the total compressor power. Due to the low compressed air temperatures, the compressor efficiency is also low. The compressed air temperature is often cooled to as low as 70° F. and the air volume reduced by as much as 10%. Therefore, as much as 10% more compressed air is used for the same purpose. In general, the current compressed air system (excluding the distribution system) often uses 20% to 45% more energy than necessary.

Ideally, a system would be devised that can resolve the system drawbacks in the prior art. However, at the current time there is no known method or system which accomplishes this objective. Therefore, it is an object of an embodiment of the proposed system to provide an improved air compressor system that not only reduces equipment costs and the compressor head, but that also reduces the energy consumption of the compressor. It is a further object of an embodiment of the proposed system to include a VFD modulated fan, air filter, process air filter, and dryers as well as to simplify the operational and maintenance requirements.

Accordingly, it is one aspect of an embodiment to reduce the equipment costs and compressor head by eliminating the need for the after-cooler, moisture separator, and heaters. The compressor power can be reduced by as much as 10% as a result.

It is another aspect of an embodiment to provide the pressure head needed to overcome the resistance of the air filter, process air filter, and dryer in order to increase the system efficiency by as much as 25% the compressor efficiency.

It is yet a further aspect of an embodiment to maintain a relatively high supply air temperature to prevent condensation in the distribution system and to reduce compressed air use by as much as 10%.

SUMMARY OF THE INVENTION

The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to an embodiment of the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

In an embodiment, a system for compressing a quantity of air is proposed. The air compressor system is comprised of an air compressor for compressing a quantity of air, a supply air fan in connection with the compressor and operable to supply air to maintain a pressure set point at the inlet of the compressor, a static pressure sensor in connection with the compressor and configured to detect the static pressure at the inlet of the compressor. The embodiment also includes a variable frequency drive serving the supply air fan and functions to modulate the speed of the fan to maintain the static pressure at the inlet of the compressor at a set point. The embodiment also comprises an air pressure regulator valve in connection with the compressor and operable to regulate the air pressure of the quantity of air. An air pressure receiver is configured in electrical communication with the air pressure regulator valve and is operable to store air in order to minimize a fluctuation in the pressure.

The compressor can be lubricant injected or lubricant free. In an embodiment in which it is lubricated, an air separator may be provided that functions to separate the lubricant from the air. In embodiments with a lubricated compressor, a lubricant cooler may also be provided in connection to the compressor that functions to cool the lubricant. Additionally, in some embodiments one or more filters may be provided upstream of the compressor to remove undesired particulate matter from the air. In some embodiments, a dryer is provided upstream of the air compressor, the dryer having a drying agent for removing moisture from the air that is fed through the outlet of the compressor. Finally, an embodiment with a dryer may also include an air by-pass damper connected to the compressor and configured to enable the air to bypass the damper. Notably, unlike prior art compressor systems, the dryer and filters are located upstream of the compressor. This enables the air compressor system to achieve higher energy savings.

An embodiment may include a method of decreasing the volume and increasing the pressure of a quantity of air, wherein a compressor having an inlet is provided in contact with a quantity of air and functions to compress that air. The method includes providing a supply fan to maintain the static pressure set point at the inlet of the compressor. A static pressure sensor is provided in connection with the compressor to detect the static pressure at the inlet of the compressor. In the method, a variable frequency drive is provided in electrical communication with the supply fan and modulates the speed of the fan in order to maintain the static pressure of the inlet of the compressor at a set point. An air pressure regulation valve is provided to regulate the pressure of the quantity of air, and an air pressure receiver provided to store the quantity of air. In other embodiments of the method, the quantity of air passes through a dryer or air bypass damper, and/or at least one air filter. In yet other embodiments of the method, the compressor may be injected with lubricant and a coalescing separator and/or air separator thus provided in order to separate the lubricant from the air. A lubricant cooler may also be provided in the embodiment to cool the lubricant. If a dryer and air filters are located upstream of the compressor in embodiments of the method in which they are provided to save energy.

The above-described features and advantages of the present disclosure thus improve upon aspects of those systems and methods in the prior art designed to compress air.

BRIEF DESCRIPTION OF THE DRAWINGS

It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the following figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Advantages, features and characteristics of the present disclosure, as well as methods, operation and functions of related elements of structure, and the combination of parts and economies of manufacture, will become apparent upon consideration of the following description and claims with reference to the accompanying drawings, all of which form a part of the specification, wherein like reference numerals designate corresponding parts in the various figures, and wherein:

FIG. 1 is a schematic diagram of an air compressor system in the prior art.

FIG. 2 is a schematic diagram of the system embodying the principles of the invention used for compressing air.

PRIOR ART DRAWINGS REFERENCE NUMERALS

-   100 Air Compressor System (prior art) -   102 Air Filter (prior art) -   104 Compressor (prior art) -   106 Lubricant Cooler (prior art) -   108 Air Separator (prior art) -   110 Coalescing Separator (prior art) -   112 After Cooler (prior art) -   114 Moisture Separator (prior art) -   116 Dryer (prior art) -   118 Air Filter (prior art) -   120 Air Receiver (prior art) -   122 Heater (prior art) -   124 Pressure Regulation Valve (prior art)

DRAWING REFERENCE NUMERALS

-   200 Air Compressor System -   202 Supply Air Fan -   204 Air Filter -   206 Process Air Filter -   208 Dryer -   210 Air By-pass Damper -   212 Static Pressure Sensor -   213 Compressor -   214 Lubricant Cooler -   216 Air Separator -   218 Coalescing Separator -   220 Air Receiver -   222 Air Pressure Regulator Valve -   224 VFD

DETAILED DESCRIPTION

Before the present methods, systems and materials are described, it is to be understood that this disclosure is not limited to the particular methodologies, systems and materials described, as these may vary. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, an is not intended to limit the scope.

FIG. 2 shown below illustrates an embodiment of air compressor system 200 for decreasing the volume and increasing the pressure of a quantity of air. Air compressor system 200 is comprised of supply air fan 202, medium air filter 204, process air filter 206, dryer 208, air bypass damper 210, static pressure sensor 212, compressor 213, lubricant cooler 214, air separator 216, coalescing separator 218, air receiver 220, and air pressure regulator valve 222. Compressor 213 has an inlet and an outlet. Air is fed into the inlet of the compressor and is compressed by compressor 213. The air then exists via the outlet of the compressor. Supply air fan 202 is connected to air compressor 213 and supplies air to overcome pressure losses through medium air filter 204, process air filter 206, and dryer 208. Supply air fan 202 also functions to maintain the required pressure set point at the inlet of compressor 213. Medium air filter 204 is connected to supply air fan 202 and functions to remove particles from the air. Process air filter 206 is connected to air filter 204 and functions to improve the air quality by removing oil, water, and/or particulates that accumulate as a result of the compression processes. Although included in the embodiment illustrated in FIG. 2, air filter 204 is not needed in alternative embodiments and in different contexts. In manufacturing plant applications, for example, a filter is not needed, while a high performance filter is required for instrument and process applications. A special filter must be selected for contexts such as the food industry, pharmaceutical and electronic processes. For example, a 5 um filter is best used for fine finishes, powder coating, and food processing, while 20 um filters are typically used for motors, rock grinders, and drills.

Dryer 208 is connected to process air filter 206 and configured to remove moisture from the air. The type of dryer used depends on the moisture requirement of the compressed air and may not be needed in certain contexts such as under typical manufacturing plant conditions. Refrigeration cooling is used instead of a dryer for instrument applications and/or when outside air is used. Other dryers can be employed when the moisture content in the air is low. Air bypass damper 210 is connected to process air filter 206 and compressor 213. The function of air bypass damper 210 is to make it possible for air to bypass the dryer. Bypassing the dryer also results in a reduction of pressure losses and saved fan power energy. Static pressure sensor 212 is connected in the ductwork between dryer 208 and compressor 213. The pressure sensor measures the static pressure of the entering air of compressor 213. Compressor 213 can be connected to dryer 208. The compressor can be either lubricant free or lubricant injected. Lubricant cooler 214 is configured to cool the lubricant to a level at which the safety and efficiency of the compressor is maintained. Air separator 216 is configured in communication with compressor 213 and coalescing separator 218 and functions to separate the air and lubricant should compressor 213 be an injected lubricant compressor. In embodiments in which compressor 213 is not lubricant injected, air separator 216 and coalescing separator 218 are not needed. Coalescing separator 218 is configured in communication with air separator 216 and air receiver 220 and functions to separate the lubricant out from the air stream. Air pressure receiver 220 is configured in communication with air pressure regulator valve 222 and functions to store the amount of air needed to minimize the pressure fluctuation in case of a load change. Air pressure regulator valve 222 regulates the air pressure to the level needed by the process equipment. VFD 224 is configured in communication with supply air fan 202 and modulates the speed of the fan to maintain static pressure sensor 212 at the set point.

It will be apparent to those skilled in the art that various modifications can be made in the system for optimizing an air compressor system without departing from the scope or spirit of the given embodiment. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure in this application. 

What is claimed is:
 1. An air compressor system for decreasing the volume and increasing the pressure of a quantity of air having an air compressor formed with an inlet and outlet, said air compressor system comprising: a supply air fan connected in electrical communication with said compressor and operable to maintain a pressure set point at said inlet of said compressor; a static pressure sensor connected in electrical communication with said compressor and configured to detect a static pressure at said inlet of said compressor; a variable frequency drive connected in electrical communication with said supply air fan and configured to modulate the speed of said fan to maintain said static pressure at said inlet of said compressor. an air pressure regulator valve in connection with said compressor and operable to regulate said air pressure of said quantity of air; an air pressure receiver configured in electrical communication with said air pressure regulator valve and operable to store air for minimizing a fluctuation in said pressure;
 2. The air compressor system of claim 1, wherein said air compressor is injected with a lubricant.
 3. The air compressor system of claim 2, further comprising an air separator configured in communication with said compressor and operable to separate out said lubricant from said quantity of air.
 4. The air compressor system of claim 2, further comprising a coalescing separator configured in communication with said compressor and operable to separate said lubricant from said quantity of air.
 5. The air compressor system of claim 2, further comprising a lubricant cooler configured in communication with said compressor and operable to cool said lubricant.
 6. The air compressor system of claim 1, further comprising at least one air filter connected upstream of said air compressor and operable to remove undesired matter from said quantity of air.
 7. The air compressor system of claim 1, further comprising a dryer configured upstream of said air compressor, said dryer having a drying agent for removing moisture from said quantity of air fed through said outlet of said air compressor;
 8. The air compressor system of claim 7, further comprising an air by-pass damper connected in electrical communication with said compressor and configured to enable said quantity of air to bypass said damper.
 9. A method of decreasing the volume and increasing the pressure of a quantity of air, said method comprising: providing an air compressor formed with an inlet and outlet in contact with said quantity of air; compressing, by said air compressor, said quantity of air; providing a static pressure sensor in connection with said compressor; detecting, by said static pressure sensor, a static pressure of said quantity of air; providing a supply fan in electrical communication with said compressor; maintaining, by said supply fan, a pressure set point at said inlet of said compressor; providing a variable frequency drive in electrical communication with said supply fan; modulating, by said variable frequency drive, a speed of said fan to maintain said static pressure at said inlet of said compressor at a set point. providing an air pressure regulator valve in connection with said compressor; regulating, by said air pressure regulator valve, said pressure of said quantity of air; providing an air pressure receiver in communication with said air pressure regulator valve; storing, by said air pressure receiver, said quantity of air.
 10. The method of claim 1, further comprising providing at least one air filter upstream of said compressor, and removing, by said air filter, undesired matter from said quantity of air.
 11. The method of claim 1, further comprising injecting said compressor with a lubricant.
 12. The method of claim 11, further comprising providing a lubricant cooler in communication with said compressor and cooling, by said lubricant cooler, said lubricant.
 13. The method of claim 11, further comprising providing a coalescing separator in communication with said compressor and separating, by said coalescing separator, said lubricant from said quantity of air.
 14. The method of claim 11, further comprising providing an air separator in communication with said compressor and separating, by said air separator, said lubricant from said quantity of air.
 15. The method of claim 1, further comprising providing a dryer configured upstream of said air compressor and removing, by said dryer, moisture from said quantity of air at said outlet of said compressor.
 16. The method of claim 15, further comprising providing an air bypass damper in connection to said compressor. 